DELTA 1010's - Anybody successfully using 2 or 3 together?

Hello digital hardware people.....I have 3 MAudio Delta 1010 A/D/A's (24 channels total of analog I/O) and I'm having a problem getting them to play nice together. I'm thinking this is a clocking issue. The 1st box is running on it's internal xtal and the other 2 boxes are SUPPOSED to be slaves.....using the master clock of the 1st box through SPDIF connections.

Recording up to 24 tracks through the hardware INs? No problem.

Piping more than 8 tracks out individually for analog mixdown? All the hardware OUTs of the 2nd and 3rd boxes go into a 'stuttering loop' immediately upon playback. They reset only when I close the application I'm running.

I accidentally found a quirky 'workaround' to this problem. When I first boot up, if I open up a project in Vegas FIRST, then close it and open my Nuendo project, all is well. I can successfully bus out 24 tracks to the H/W outs of my Delta boxes.

But if I boot up, and try to open a Nuendo project first, I can only bus out the first 8 H/W outs, the rest of the H/W outs give me clipped digital garbage.

dab - Yes, I am using the (supposed) proper settings in the DELTA control panel. The cards are physically linked through SPDIF, which is how the 2nd and 3rd boxes are supposed to get their clock (from the 1st box's internal crystal).

There are also BNC word clock IN/OUT's on each box. I'm now wondering if I use these connections INSTEAD of the SPDIF connections, if I might not solve the problem. It's what I'm going to try next anyway.

I purchased a Lucid word clock generator. Problem solved and I can tell a difference in audio quality, which I was skeptical about. The sound stage just seems deeper, with better detail. The sonic difference is especially noticeable in the tails of reverb.